Fully Homomorphic Encryption (FHE) is a cryptographic method that guarantees the privacy and security of user data during computation. FHE algorithms can perform unlimited arithmetic computations directly on encrypted data without decrypting it. Thus, even when processed by untrusted systems, confidential data is never exposed. In this work, we develop new techniques for accelerated encrypted execution and demonstrate the significant performance advantages of our approach. Our current focus is the Fully Homomorphic Encryption over the Torus (CGGI) scheme, which is a current state-of-the-art method for evaluating arbitrary functions in the encrypted domain. CGGI represents a computation as a graph of homomorphic logic gates and each individual bit of the plaintext is transformed into a polynomial in the encrypted domain. Arithmetic on such data becomes very expensive: operations on bits become operations on entire polynomials. Therefore, evaluating even relatively simple nonlinear functions, such as a sigmoid, can take thousands of seconds on a single CPU thread. Using our novel framework for end-to-end accelerated encrypted execution called ArctyrEX, developers with no knowledge of complex FHE libraries can simply describe their computation as a C program that is evaluated over $40\times$ faster on an NVIDIA DGX A100 and $6\times$ faster with a single A100 relative to a 256-threaded CPU baseline.

翻译：全同态加密（FHE）是一种能够在计算过程中保障用户数据隐私与安全的密码学方法。FHE算法可直接对加密数据执行无限算术运算而无需解密，因此即便在不可信系统中处理，机密数据也永不泄露。本研究开发了加速加密执行的新技术，并展示了该方法显著的性能优势。当前聚焦于环面全同态加密（CGGI）方案，该方案是加密域中任意函数评估的最先进方法。CGGI将计算表示为同态逻辑门图，且明文的每个独立比特会被转换为加密域中的多项式。此类数据的算术运算代价极高：对比特的操作将转化为对整个多项式的操作。因此，即使评估sigmoid等相对简单的非线性函数，在单个CPU线程上也需耗时数千秒。通过我们所开发的全流程加速加密执行框架ArctyrEX，无需掌握复杂FHE库知识的开发者仅需将计算描述为C程序，即可在NVIDIA DGX A100上实现超过40倍的加速比，在单个A100上实现相对于256线程CPU基线的6倍加速比。